90 EDWIN G. CONKLIN 
Lors, J. 1899 Warum ist die Regeneration kernléser Protoplasmastiicke un- 
moglich oder erschwert? Arch. f. Entw. Mech., Bd. 8. 
1909 Die chemische Entwicklungserregung des tierischen fies. Ber- 
lin, 1909. 
1910 Ueber den autokatalytischen Charakter der Kernsynthese bei 
der Entwickelung. Biolog. Centralb., Bd. 30. 
Lyon, E. P. 1904 Rhythms of susceptibility and of carbon dioxide production 
in cleavage. Am. Jour. Physiol., vol. 11. 
1907 Results of centrifugalizing eggs. Arch. f. Entw. Mech., Bd. 23. 
Masine, EB. 1910 Ueber das Verhalten Neucleinsiure bei der Furchung Seeig- 
leies. Hoppe-Seylers Zeitschrift. Bd., 67. Review by Godlewski, Arch. 
f. Entw. Mech., Bd. 31. 
Minot, C. S. 1890 On certain phenomena of growing old. Proc. Amer. Ass’n 
Adv. Sci., vol. 29. 
1895 Ueber die Vererbung und die Verjungung. Biol. Central., Bd. 15. 
1908 Age, growth and death. Putnams, New York. 
Monteomery, T. H. 1910 On the dimegalous sperm and chromosomal variation 
of Euschistus, with reference to chromosomal continuity. Arch. f. 
Zellforschung, Bd. 5. 
Morean, T. H. 1910 Experiments bearing on the nature of the karyokinetic 
figure. Proc. Soc. Exp. Biol. and Medicine, vol. 7. 
Peter, K. 1906 Der Grad der Beschleunigung tierischen Entwicklung durch 
erhéhte Temperatur. Arch. f. Entw. Mech., Bd. 20. 
Pororr, M. .1908 Experimentelle cytologische Studien. Arch. f. Zellforschung, 
1BYele ale 
SHACKELL, L. F. 1911 Phosphorus metabolism during early cleavage of the 
echinoderm egg. Science, vol. 34, no. 878. 
STRASBURGER, E. 1893 Ueber die Wirkungssphire der Kerne und die Zell- 
grésse. Histolog. Beitrige, Bd. 5. 
VerRworn, M. 1891 Die physiologische Bedeutung desZellkernes. Arch. f. 
d. ges. Physiol., Bd. 51. 
WatTase, 8. 1893 On the nature of cull organization. Woods Hole Lectures. 
Wiutson, E. B. 1904 Experimental studies on germinal localization. Jour. 
Exp. Zool., vol. 1. 
DESCRIPTION OF FIGURES 
All figures (with the exception of figs. 9 and 10) represent entire eggs of Crepid- 
ula plana, fixed, stained, and mounted on slides. They were drawn with the aid 
of a camera lucida under Zeiss Apochromat 8 mm., Ocular 4, and represent a mag- 
nification of 333 diameters. In the centrifuged eggs, the axis of centrifuging is, 
in many cases, indicated by an arrow, the head of the arrow marking the distal 
(heavy) pole and the tail of the arrow the central (light) pole. In figs. 12 to 19, 
and 29 to 37 the first cleavage is in the long axis of the page, the second cleavage 
(figs. 18 and 19) is at right angles to this. In figs. 21 to 28 the first cleavage runs 
across the page, the second, lengthwise of it. 
